Glass blocks reimagined
The PLEXIGLAS® brand
Semi-finished polymethyl methacrylate (PMMA) products from POLYVANTIS are sold on the European, Asian, African and Australian continents under the registered trademark PLEXIGLAS®, in the Americas under the registered trademark ACRYLITE®, both owned by Röhm GmbH, Darmstadt, or its affiliates.
At the Glass Competence Center at TU Darmstadt, a team is researching how to use glass as a construction material in buildings. Now the scientists’ years of research have been put to practical use in the form of a glass bridge – in which PLEXIGLAS® acrylic elements play a crucial role.
At first glance, the Glassbridge looks to be a highly fragile structure made entirely of glass. Spanning almost ten meters, this curved glass bridge is on display at the Corning Museum of Glass in New York until September 2025. But spend a little longer admiring the futuristic structure and you’ll see that it is entirely safe and stable. “The Glassbridge demonstrates that it is possible to use glass as a construction material,” explains Philipp Amir Chhadeh, a research associate at TU Darmstadt’s Glass Competence Center (GCC). Together with a team from the University of Pennsylvania, led by Dr. Masoud Akbarzadeh, the GCC developed the innovative building method that gives the bridge its stability. And this unique design would not have been possible without components made from PLEXIGLAS® acrylic.
Geometry-based design
“Glass is extremely resistant to pressure, but tension is a problem,” Chhadeh explains. This is why the developers opted for an arch shape, since – under a uniform load – this type of construction only exerts a compression force on each component. “We started with the idea of developing a new type of glass block that boosts this property even further,” Chhadeh tells us. These new blocks are called hollow glass units, or HGUs.
The Glassbridge is put together from 124 of these honeycomb-like blocks. The HGUs were developed using a geometry-based structural design method known as polyhedral graphic statics. The 124 units are formed to fit together perfectly and create the arch shape.
Each unit consists of two top panels, connected by side panels. The top panels consist of composite glass made from two 6 mm panes of float glass, which ensures a residual load-bearing capacity should one fail. The side panels serve to transfer load from the upper top panel to the lower top panel, as well as connect the HGUs. “To meet this requirement profile, we use PLEXIGLAS® acrylic because it can be processed highly precisely with CNC milling, and is highly stable and transparent,” explains Chhadeh.
Properties of PLEXIGLAS® GS:
- High transparency and glass-like appearance
- Low weight
- High break resistance and surface hardness
- Easy to handle and process
Precision with PLEXIGLAS® acrylic
The glass panels and side parts are bonded together using VHB (very high bond) adhesive tape, and the HGUs are then inserted into each other using a linking block.
“We spent a long time thinking about how to build the blocks entirely from glass, but it proved very difficult,” says Chhadeh. “This type of construction of the side panels demands very thick glass with a milled undercut. The problem with glass is the low strength of this drilled hole. “We therefore needed a material that would be easier and more cost-effective to process, but still work well together with glass. Our choice was PLEXIGLAS® acrylic.”
For the construction of the Glassbridge, the team opted for PLEXIGLAS® GS 0F00 GT in a thickness of 25 millimeters. Its specific properties – such as precision processing, stability and transparency – make it the ideal material for this ambitious project.
In the Glassbridge, PLEXIGLAS® sheets were used for the connecting elements inside the HGUs and for the key blocks. “The material can be processed so precisely that we were able to produce all 124 units with a tolerance of less than one millimeter,” Chhadeh notes. With such an innovative construction, this was crucial – the bridge would only work if all the elements meshed together perfectly.
“Using a combination of PLEXIGLAS® sheets from POLYVANTIS and glass, we had the HGUs produced in Germany by Glasbau Pritz and then assembled the Glassbridge together with the team from the University of Pennsylvania,” reports Chhadeh.
Glass as a construction material
For now, the Glassbridge is a prototype. “Our calculations are based on the specific case of one person walking over the bridge,” explains Philipp Amir Chhadeh, who was responsible for the structural analysis of the glass as a member of the team from TU Darmstadt’s Glass Competence Center. “It has not yet been designed for larger numbers of people.” However, this is the long-term goal – and not just for the Glassbridge. The institute is working on ways to integrate as much glass as possible into buildings as a construction material.
UV and weather-resistant material
The team used a wooden substructure as a base when putting the individual units together. “During the assembly process, it was helpful that PLEXIGLAS® sheets are much lighter than glass – this reduced the overall weight of the individual HGUs.” But it wasn’t just the excellent processing characteristics and low weight that led the developers to PLEXIGLAS® GS 0F00. “We also chose it because of its high transparency.” PLEXIGLAS® acrylic looks virtually identical to glass, so it fits harmoniously with the bridge’s overall appearance. The material’s excellent surface hardness and long-lasting resistance to UV and weathering ensure strong resistance against the elements and a long service life. The transparency and glass-like appearance of PLEXIGLAS® acrylic components do not diminish over time, as the UV-stable material does not turn yellow when exposed to sunlight.
Fully recyclable
The innovative bridge project sets new standards – not just in technical terms, but also when it comes to sustainable construction and aesthetic design. “Building bridges from glass and PLEXIGLAS® sheets is less resource-intensive than steel constructions,” explains Chhadeh. Another plus is the recyclability of the materials used. Both glass and PLEXIGLAS® sheets can be fully recycled at the end of their service life. “Since the HGUs are simply stuck together, they can be taken apart again at the end of their life.” And if one unit is damaged, the modular design comes into play: “It’s as simple as setting up the substructure again and replacing the defective unit with a new one.”
For Chhadeh, the most important attribute of glass is its transparency. “A building without any transparent elements is deprived of natural light. Glass makes every building better.” Exceptional transparency is also the key property of acrylic from the PLEXIGLAS® brand. The team’s work on the Glassbridge illuminated how – with its glass-like appearance, lightweight construction, and good processing characteristics – it will continue to help bring unique projects to life in the future.
